One-dimensional stability analysis of a hydraulic system composed of a penstock, a runner, and a draft tube was carried out to determine the cause of the full load draft tube surge. It is assumed that the cavity volume at the runner exit is a function of the pressure at the vortex core evaluated from the instantaneous local pressure at the runner exit and an additional pressure decrease due to ...

— Vortices can be produced and ingested into the intake of a jet engine during high power operation in the vicinity of solid surfaces causing Foreign Object Damage (FOD) or compressor stall and engine surge problems. This can occur when the engine is mounted on the wing of a plane during takeoff and engine ground runs or when the engine is placed inside a test cell for testing after an engine o...

The stretched-spiral vortex model is used to calculate the velocity-scalar cross spectrum for homogeneous, isotropic turbulence in the presence of a mean scalar gradient. The only nonzero component of the cospectrum is that contributed by the velocity component in the direction of the imposed scalar gradient while the quadrature spectrum is identically zero, in agreement with experiment. For th...

Dust particles charging in a stratified positive column of a low-pressure DC glow discharge was investigated theoretically. The presented model consists of (i) previously developed 1D selfconsistent model for discharge parameters on the tube axis; (ii) ambipolar approximation for radial electric potential distribution and the assumption that the electron energy distribution function in radial d...

Acoustic resonances in Francis turbines often define undesirable limitations to their operating ranges at high load. The knowledge of the mechanisms governing the onset and the sustenance of these instabilities in the swirling flow leaving the runner is essential for the development of a reliable hydroacoustic model for the prediction of system stability. The present work seeks to study experim...

Abstract We have carried out numerical simulation of the flow in jet mill ejector. The features ejector are an annular unit for supplying additional gas form a confuser section at inlet to accelerating tube, as well outlet tube. In course study, we varied length and angle supply. established optimal parameters ejector, which it has been most uniform distribution velocity use scheme under study ...

Under low flow-rate conditions, a Francis turbine exhibits precession of vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration performance as manifested by torque and power output fluctuations. In order suppress swirl component tube, use anti-swirl fins was investigated previous study. However, generation still occurred near cone th...

Plasma based therapeutic products must undergo viral inactivation steps in order to minimize the risk of infection. Non-enveloped viruses such as hepatitis A and parvovirus are more recently being inactivated by using Ultra Violet light C (UV-C) irradiation techniques. A commonly used form of UV-C irradiation involves passing the protein solution through a helical tube that wraps around an irra...

We consider the steady propagation of an air finger into a buckled elastic tube initially filled with viscous fluid. This study is motivated by the physiological problem of pulmonary airway reopening. The system is modelled using geometrically non-linear, Kirchhoff–Love shell theory coupled to the free-surface Stokes equations. The resulting three-dimensional fluid-structure-interaction problem...